A Sensitive Dot Immunoassay Employing Monoclonal Antibodies for Detection of Sirococcus strobilinus in Spruce Seed. Leslie Ann Mitchell, Research Scientist, Canadian Forestry Service, Pacific Forestry Centre, 506 W. Burnside Rd., Victoria, B.C., Canada V8Z 1M5. . Plant Dis. 72:664-667. Accepted for publication 19 February 1988. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0664.

A qualitative, highly sensitive dot immunobinding assay for detection of the pathogenic fungus Sirococcus strobilinus on spruce seed is described. This assay employs S. strobilinus-specific monoclonal antibodies to detect fungal material (antigens) in spruce (Picea spp.) seed extracts applied in small volumes (0.5–1 ?l) to nitrocellulose paper. The dot immunoassay allows detection of as little as 1 ng of S. strobilinus antigen in fungal extracts making it 5–25 times more sensitive than the enzyme-linked immunosorbent assay (ELISA) previously described. This assay is relatively easy to perform, requires minimal laboratory equipment, and is potentially applicable for use in seed testing laboratories.